virus displaySAKCHAI LALIT/AP/Press Association Images

The FBI has issued a warning regarding the 'Alureon' virus. This started infecting computers around the world at the end of last year and initially infiltrated around 570,000. It works by redirecting you when you visit legitimate sites - taking you to spoof ones that are designed to steal your personal information. The FBI took the step of setting up a safety net, routing infected computers through their systems in order to stop the attacks.

On Monday this safety net will be cut off, and if you are infected you will be locked out of the internet.

Cut off

The attacks started when infected adverts were posted around the web, and those who clicked on them would automatically download the virus. They would then be redirected to spoof sites instead of real ones whenever they were online, and they would be encouraged to reveal sensitive data about themselves.

The FBI tracked down the hackers, but realised that if they turned off the servers owned by the hackers, those with infected computers would lose their internet connection. Instead, they set up the safety net to re-route the infected computers back to legitimate sites.

There have been a number of warnings since the attacks started, and users have been encouraged to check if their computer is infected, and take steps to protect themselves if it is. As a result of different campaigns, the number of infected computers has fallen to 277,000.

The FBI has taken the decision, therefore, to turn off the re-routing. Anyone who is still infected will therefore lose their internet connection at 4.01am on Monday (midnight in the US). They will need to contact their internet service provider and get help deleting the virus before they will be able to get back online.

There are also concerns because the virus is very good at spreading across networks, so may have infiltrated computers running vital operations within businesses. This could mean many large organisations struggling to meet their customers' needs on Monday.

Are you infected?

It is essential, therefore, to check if you are infected. The virus will have slowed your internet connection and disabled your anti-virus software, but you may not have noticed these changes. It will also have triggered warnings from Facebook and Google - both of which flash up a warning if they are visited by someone who appears to have an infected computer.

If you haven't noticed either of these, but are still worried, you can visit the site the FBI has approved. If the site has a green background then it indicates that you are probably clear. If the background is red you may be infected.

If you are infected, then you still have enough time to scan your computer and remove the malware. There are a number of services and sites that will do this for you, but a list of approved ones can be found here.